Wednesday, April 25, 2007

New 'super-Earth' found in space - BBC

Astronomers have found the most Earth-like planet outside our Solar System to date, a world which could have water running on its surface.

The planet orbits the faint star Gliese 581, which is 20.5 light-years away in the constellation Libra.

Scientists made the discovery using the Eso 3.6m Telescope in Chile.

They say the benign temperatures on the planet mean any water there could exist in liquid form, and this raises the chances it could also harbour life.

"We have estimated that the mean temperature of this 'super-Earth' lies between 0 and 40 degrees Celsius, and water would thus be liquid," explained Stephane Udry of the Geneva Observatory, lead author of the scientific paper reporting the result.

Moreover, its radius should be only 1.5 times the Earth's radius, and models predict that the planet should be either rocky - like our Earth - or covered with oceans."

Xavier Delfosse, a member of the team from Grenoble University, added: "Liquid water is critical to life as we know it."

He believes the planet may now become a very important target for future space missions dedicated to the search for extra-terrestrial life.

These missions will put telescopes in space that can discern the tell-tale light "signatures" that might be associated with biological processes.

The observatories would seek to identify trace atmospheric gases such as methane, and even markers for chlorophyll, the pigment in Earth plants that plays a critical role in photosynthesis.

'Indirect' detection

The exoplanet - as astronomers call planets around a star other than the Sun - is the smallest yet found, and completes a full orbit of its parent star in just 13 days.Indeed, it is 14 times closer to its star than the Earth is to our Sun.However, given that the host star is smaller and colder than the Sun - and thus less luminous - the planet nevertheless lies in the "habitable zone", the region around a star where water could be liquid.

Gliese 581 is much cooler and dimmer than our own SunGliese 581 was identified at the European Southern Observatory (Eso) facility at La Silla in the Atacama Desert.

To make their discovery, researchers used a very sensitive instrument that can measure tiny changes in the velocity of a star as it experiences the gravitational tug of a nearby planet.Astronomers are stuck with such indirect methods of detection because current telescope technology struggles to image very distant and faint objects - especially when they orbit close to the glare of a star.

The Gliese 581 system has now yielded three planets: the new super-Earth, a 15 Earth-mass planet orbiting even closer to the parent star, and an eight Earth-mass planet that lies further out.

Future observatories will study exoplanets for signs of biologyThe latest discovery has created tremendous excitement among scientists.

Of the more than 200 exoplanets so far discovered, a great many are Jupiter-like gas giants that experience blazing temperatures because they orbit close to hot stars.

The Gliese 581 super-Earth is in what scientists call the "Goldilocks Zone" where temperatures "are just right" for life to have a chance to exist.

Commenting on the discovery, Alison Boyle, the curator of astronomy at London's Science Museum, said: "Of all the planets we've found around other stars, this is the one that looks as though it might have the right ingredients for life.

"It's 20 light-years away and so we won't be going there anytime soon, but with new kinds of propulsion technology that could change in the future. And obviously we'll be training some powerful telescopes on it to see what we can see," she told BBC News.

"'Is there life anywhere else?' is a fundamental question we all ask."

It's been a central plank of George Bush's social policy: to stop teenagers having sex. More than $1bn of federal money has been spent on promoting abstinence since 1998 - posters printed, television adverts broadcast and entire education programmes devised for hundreds of thousands of girls and boys.

The trouble is, new research suggests that it hasn't worked. At all.

A survey of more than 2,000 teenagers carried out by a research company on behalf of Congress found that the half of the sample given abstinence-only education displayed exactly the same predilection for sex as those who had received conventional sex education in which contraception was discussed.

Mathematica Policy Research sampled teenagers with an average age of 16 from a cross-section of communities in Florida, Wisconsin, Mississippi and Virginia. Both control groups had the same breakdown of behaviour: 23% in both sets had had sex in the previous year and always used a condom, 17% had sex only sometimes using a condom; and 4% had sex never using one. About a quarter of each group had had sex with three or more partners.

Since his days as governor of Texas, George Bush has been a firm advocate of abstinence education programmes, which teach that keeping zipped up is the only certain way to avoid unwanted pregnancy and sexually transmitted diseases, and that to deviate from the norms of human sexual activity is to risk harmful psychological and physical effects. "Abstinence hasn't been given a very good chance, but it's worked when it's tried. That's for certain," he said.

But even in 1990s Texas, where Mr Bush spent $10m a year on abstinence education, the state had the fifth highest teen pregnancy rate in the US. Over the past six years he has stepped up the programme to more than $100m a year. He recently braved ridicule by extending it to adults aged 20-29, an age range in which 90% of people are sexually active.

In the Mathematica survey, which was released by sex education activists after the health department sat on it, the mean age at which the control group, that had been taught about contraception, lost their virginity was 14.9 years. That seems strikingly low, until you look at the mean age of first sexual experience for the abstinence control group - 14.9 years.

In the context of findings like this, health workers and statisticians conclude that it is far better that children have safe sex, with knowledge of and access to contraception, than that they are preached a message of abstinence only to ignore it.

Federal funding for abstinence education began as a small part of Mr Clinton's welfare reforms but was stepped up substantially by the Bush administration. Its supporters claim that the fact that though teenaged pregnancies have fallen in the US from a high of 62.1 per 1,000 women aged 15 to 19 in 1991 to 41.1 births per 1,000 in 2004 shows the campaign is working.

But the Mathematica findings, building on earlier research, cast that optimism in doubt. Anti-abstinence activists have long argued that the movement is dangerous because it leaves young people exposed to the risk of teen pregnancy and infection because the teaching shuns any mention of condoms or contraception. Of about 19m new STD infections in the US each year, almost half are recorded among people aged 15 to 24.

Friday, April 13, 2007

Monkey DNA Points to Common Human Ancestor - LiveScience

By Charles Q. ChoiSpecial to LiveScienceposted: 12 April 200702:01 pm ETThe first primate to get rocketed into space and to be cloned, the rhesus monkey, has now had its genome sequenced, promising to improve research into health and yield insights into human evolution.

Analysis of the monkey's DNA sequence has also deepened a few mysteries in our understanding of the biology of primates when it comes to vital parts of our biology, such as the X chromosome.

Rhesus macaques (Macaca mulatta) are sandy-furred, pink-faced monkeys that live in the region ranging from Afghanistan to northern India, as well as southern China, and are traditionally held as sacred in Hinduism.

They have a long history as lab monkeys. For instance, the Rh factor in blood discovered in 1937, the presence or absence of which dubs a person's blood type either 'positive' or 'negative,' derives its name from rhesus monkeys. Even now, they are the animals of choice for research into drug addiction and HIV, and roughly two-thirds of all National Institutes of Health-funded primate-related studies use the monkeys. For example, the rhesus monkey Tetra, born in 2000, was the first cloned primate.

93 percent common DNA

The sequence of the rhesus macaque's genome will be a powerful tool for research with the monkeys aimed at understanding human biology, said consortium leader Richard Gibbs, director of the Baylor College of Medicine's Human Genome Sequencing Center in Houston."Right now if you perform an experiment on a person, there's no way that you would think that all people are the same, when it comes to a response to a drug or behavior or anything," Gibbs told LiveScience. Macaques have about the range of diversity when it comes to their genetics, "so being able to understand them on a genetic level will help explain variation in their responses and will allow for smarter experiments that make us more clever at deciphering results."

The new analysis of the rhesus monkey genome, conducted by an international consortium of more than 170 scientists, also reveals that humans and the macaques share about 93 percent of their DNA. By comparison, humans and chimpanzees share about 98 to 99 percent of their DNA.

The fact that rhesus monkeys are further away from humans in evolution will help illuminate what makes humans different from other apes in ways that chimps, which are so closely related to us, could not, Gibbs said. (Rhesus monkey ancestors diverged from those of humans roughly 25 million years ago, while chimpanzees diverged from our lineage 6 million years ago.)

In addition, the researchers identified roughly 200 genes that appear to be key players "in defining the shapes of species, in what makes the primates different from us and each other," Gibbs said. These include genes involved in hair formation, sperm-egg fusion, immune response and cell membrane proteins, findings detailed in the April 13 issue of the journal Science.

Unusual role of X chromosome

The research also raised a few surprises. For instance, the monkey's X chromosome showed an unexpectedly large number of times in which its parts got shuffled around. This is consistent with the same mysterious rearrangements seen in the human lineage's X chromosome following the branching off of the chimpanzee, and gives "us new evidence of the unusual role of this sex chromosome in primate evolution," said researcher Aleks Milosavljevic at the Baylor College of Medicine.

Another as yet unexplained phenomenon the sequencing revealed has to do with lumps of DNA known as centromeres, which hold together the two separate strands of DNA that make up a chromosome, acting somewhat like the center of an X. Strangely, nine of the 22 centromeres the monkeys have repositioned themselves on their chromosomes in the last 25 million years. As to why this happened, "no one knows," said researcher Mariano Rocchi at the University of Bari in Italy.

The rhesus monkey genome sequence should prove invaluable to biomedical research, said physician scientist Ajit Varki at the University of California at San Diego, who participated in the chimpanzee genome sequencing project. "And if we can get the genome sequences of one representative from each primate lineage, we could reconstitute the ancestral primate genome—what the genome of our common ancestor some 40 to 50 million years ago looked like," he told LiveScience. "That would be an amazing feat."

Thursday, April 12, 2007

Colorful Worlds: Plants on Other Planets Might Not Be Green - space.com

By Ker ThanStaff Writerposted: 11 April 200709:01 am ETIf trees grow on other planets, their leaves might be red, orange or yellow, and not only in autumn, scientists say.

Two new studies detailed in the March issue of the journal Astrobiology find that the color of a planet’s photosynthetic organisms depend on the type of star the world orbits and the makeup of its atmosphere.

“You have a particular spectrum which is affected by the star’s surface temperature, but once that light comes down through the atmosphere, the atmosphere filters that radiation,” said study team member Victoria Meadows of the Virtual Planet Laboratory (VPL) at Caltech.

For example, our Sun radiates most of its energy in the green part of the visible spectrum. But ozone molecules in the Earth’s atmosphere absorb much of this green light energy, allowing other colors, especially red, to filter through to the ground.

“Ozone filters out some of the blue-green radiation, so there’s less of that available at the surface of the planet,” Meadows told SPACE.com.

Alternative explanations have also been proposed for the greenness of plants. One idea, called the purple Earth hypothesis, states that chlorophyll doesn’t absorb green light because it appeared after another pigment, called retinal, was already present and it had to settle for the “leftover” wavelengths that were not being absorbed.

The researchers reached their conclusions after analyzing 12 different kinds of light-sensitive pigments, including chlorophyll, that organisms on Earth use to harness the Sun’s energy.Plant biosignatures

The researchers want to use their findings to guide the search for plant life on other worlds. To that end, Meadows’ team at VPL entered the results of the pigment analysis study into a computer simulation that predicts what the light from a distant planet containing photosynthetic organisms will look like to space telescopes.

For example, in addition to reflecting back visible green light, organisms on Earth that use chlorophyll for photosynthesis also reflect near infrared light. This reflected light can be seen from space and is called the “red edge.”

The new findings suggest photosynthetic organisms on other planets might not produce a red edge, but some other biosignature instead. The researchers want to figure out what those alternative biosignatures might be.

“We’re coming up with rules so that we can say more confidently what is photosynthesis when looking at spectra from these planets,” said study leader Nancy Kiang, a biometeorologist at NASA’s Goddard Institute for Space Studies in New York.

Search for life

Whether or not scientists find life on distant worlds could depend on these rules.“When we look at these faraway planets, we’re not going to be able to spatially resolve them. We won’t be able to see continents and oceans,” Meadows said. “Everything we must learn about that planet will be in a single dot of light.”

Already, the researchers think they can already make certain generalizations about photosynthesis in the universe at large. It’s unlikely, for example, that plants on alien worlds will be blue.

“It appears that harvesting blue light is very common across the board for photosynthetic organisms” on Earth, Kiang said in a telephone interview. “I think it is unlikely that anything will be blue.”

Thursday, April 05, 2007

Are men smarter than women?

Marilyn vos Savant (born Marilyn Mach on 11 August1946) is an American magazine columnist, author, lecturer, and playwright who rose to fame through her listing in the Guinness Book of World Records under "Highest IQ".

Does the disparity between men and women in the sciences say something about their relative intelligence? Marilyn weighs in on this controversial debate.

Are Men Smarter Than Women?

Published: July 17, 2005By Marilyn vos Savant

Dear Marilyn: How do you view the idea that the gender disparity in the sciences might be due to differences in the inherent aptitudes of women? I’m curious to hear a thoughtful and objective opinion on this controversial subject.—Melissa Hardison, Tallahassee, Fla.

A gender gap exists in many occupations, but the disparity in the sciences hits close to one of the scariest marks of all, which is the reason a controversy erupted: Are men smarter than women?

The concern unfolds in two questions: 1) Are women handicapped by their upbringing, social pressures, discrimination from men, and more—not just in science but also in other areas? 2) Or are women less bright than men?Some AnswersThe answer to the first question is too obvious for argument: Yes, and in my opinion, upbringing is the No. 1 cause—not discrimination, conscious or not, from men. Just as significant is the fact (not the problem) that many women are far more interested in their families than outside work, and society clearly approves. Top positions do require time, energy and dedication to goals that may even be selfish.The second question is the hot spot. The average IQ of females is equal to the average IQ of males. But averages can be misleading. In the case of intelligence tests, many more males score at the top and the bottom of the intelligence scale. This could account for the greater number of men in the sciences and—on the other end—in the prison population. So: Does the gender disparity in science give credence to the idea that men are more intelligent than women? My answer is “no,” and these are my reasons:

•No evidence indicates that the sciences attract the brightest people. The unspoken assumption that science attracts the smartest people is the foundation upon which we have built the conclusion: “If the sciences are filled with men, men must be smarter, unless women have a good excuse for being absent.” I believe that science—like chess— attracts bright people, but only the ones with certain personality characteristics. Those traits might be more common in men. In the case of chess, the game was developed by males for intellectual sparring with other males. Maybe females simply don’t find the game as fascinating. And note that dictators—who aren’t any stronger than other men—are never women. Maybe females just don’t have whatever it takes to bulldoze their way to this dubious sort of “success.” No one thinks the paucity of women in the field of ruthless domination is because they aren’t smart enough! So why should anyone be shocked to find that most bright people—including women—would flee from the sight of a microscope?!To me, it is clear that the brightest people are spread over all sorts of other occupations. Motherhood is likely among them, and why not? I was a stay-at-home mom while my children were small, and I loved it.

•Even professionally administered IQ tests are primitive measures of intelligence. Intelligence tests are fine for practical purposes, but not for analytical ones. Too much unavoidable bias (not prejudice) is present: Any test-maker (not just IQ test-creators) must first develop standards upon which the test-takers will be judged. In other words, to test intelligence, the designer must formulate a definition of intelligence. Now, who could possibly do this?

Can Intelligence Be Defined?In my opinion, defining intelligence is much like defining beauty, and I don’t mean that it’s in the eye of the beholder. To illustrate, let’s say that you are the only beholder, and your word is final. Would you be able to choose the 1000 most beautiful women in the country? And if that sounds impossible, consider this: Say you’re now looking at your picks. Could you compare them to each other and say which one is more beautiful? For example, who is more beautiful— Katie Holmes or Angelina Jolie? How about Angelina Jolie or Catherine Zeta-Jones? I think intelligence is like this. So many factors are involved that attempts to measure it are useless. Not that IQ tests are useless. Far from it. Good tests work: They measure a variety of mental abilities, and the best tests do it well. But they don’t measure intelligence itself.Perhaps most convincing of all are these facts from other outposts in the animal kingdom:

•Female chimpanzees learn complex tasks as easily as males.

•Female gorillas can be taught sign language as well as males.•Female guide dogs are as capable at their work as males.

•Female dolphins perform practical jokes as often as males.•Female parrots are able to mime and talk as well as males.

•Female rats and mice run mazes just as efficiently as males.

Would you prefer to adopt a male puppy because you thought you could teach him more tricks? No, you know better. (And we don’t find more female moths in our light fixtures!) Why should anyone think that human females are an exception?!

Who's Smarter?When asked that question, PARADE columnist Marilyn vos Savant and her husband, Dr. Robert Jarvik, instinctively point to each other. Marilyn, of course, was in the Guinness Book for having the highest IQ ever recorded. But Dr. Jarvik—inventor of the Jarvik-7 and Jarvik-2000 artificial hearts, used to support patients with congestive heart failure—is no intellectual lightweight either. What do they talk about over dinner? “Medicine and world affairs are the main topics of discussion,” says Marilyn. “For entertainment, we love music, dance and going to movies.” Both are avid runners but don’t enjoy sports and never play games. Marilyn adds, “Rob is more competitive than I am—but, then again, everybody is!”

The infinite variety of our mindsJust a glance at these bright high-achievers—men and women who have made their mark in an array of fields—tells us that intelligence is complex and multi-dimensional. Comparing one to the other is like comparing apples and oranges.

The football-field sized holes were observed by Mars Odyssey's Thermal Emission Imaging System (THEMIS) and have been dubbed the seven sisters --Dena, Chloe, Wendy, Annie, Abbey, Nikki and Jeanne--after loved ones of the researchers who found them. The potential caves were spotted near a massive Martian volcano, Arisa Mons. Their openings range from about 330 to 820 feet (100 to 250 meters) wide, and one of them, Dena, is thought to extend nearly 430 feet (130 meters) beneath the planet's surface.

The researchers hope the discovery will lead to more focused spelunking on Mars."Caves on Mars could become habitats for future explorers or could be the only structures that preserve evidence of past or present microbial life ," said Glenn Cushing of Northern Arizona University, who first spotted the black areas in the photographs.

A project here on Earth aims to refine the visual and infrared techniques THEMIS used to find the Martian caves and to also develop robots that can one day enter the caverns and explore them.

Practicing on Earth

Called the Earth-Mars Cave Detection Program, the project is preparing to enter phase 2, during which scientists will test their approach in "Mars analogue" sites, terrestrial environments with similarities to Martian landscapes. These sites will include dry, blistering deserts, such as the Mojave in California and the Atacama in Chile, as well as frigid environments like Iceland and Antarctica.

During the first phase of the project, the researchers acquired the thermal signatures of a dozen caves in Arizona and New Mexico using an experimental infrared detector, called the Quantum Well Infrared Photodetector (QWIP), flown aboard an airplane.

Cave detection using QWIP works by spotting regions in the landscape where temperatures are different from the surroundings. Inside a cave, temperatures are nearly constant due to lack of sunlight. Outside, temperatures fluctuate with the rising and setting of the Sun. At a cave entrance, these two temperature regimes mix together to create a unique thermal signature that, depending on the time of day, can be either warmer or cooler than the surrounding environment.

"The caves show up as hotspots in a sea of cold, or as cold spots in a sea of warmth," said study team member Murzy Jhabvala, chief engineer of NASA's Instrument Systems and Technology Center.

The data, still being analyzed, look promising. In one series of images, the researchers snapped thermal images of Xenolith Cave in New Mexico over a 24-hour period. The cave opening can be seen clearly in some of the images.

"It jumps out at you," said Jut Wynne, a biospeleologist (cave biologist) with the U.S. Geological Survey and Northern Arizona University. "It lights up like a Christmas tree in the predawn and in the late-night shots. It's a bit more ephemeral during the day shots."In Phase 2, the researchers will tweak their technique to figure out the best wavelengths to use and optimal times during the day for cave hunting. "In so doing, we're going to take these applications and then apply them to an orbiter platform for Mars," Wynne said.

Robotic cave explorers

The project team also aims to design robots that can explore caves on Mars after they have been spotted. Natalie Cabrol, a planetary geologist with NASA Ames and the SETI Institute, will be integral to this part of the project.

Cabrol is a Mars robot veteran. Before Spirit and Opportunity were sent to Mars, she helped engineers perfect their designs by field-testing the robotic rovers in the Atacama Desert in Chile.

The researchers may have to design more than one type of robotic cave explorer. "There are many types of caves," Cabrol said in a telephone interview. "It may be that we come up with one very versatile design ... or we might end up with several designs."

If the caves have a relatively simple structure--like lava tubes, which are caves carved by flowing magma and are relatively simple and straight--a rover-type robot might work, Cabrol said. "I would doubt that a rover, equipped as they are now, would do a good job in a cave" with a more complicated geometry, she said.

Open to ideas

The researchers are also considering other robotic design possibilities, including the deployment of several miniature robots together into a cave.

"You could throw out an array of microbots in a birdshot approach over an area where you think there is a cave," Wynne told SPACE.com . The microbots could then use sonar or some other method to confirm the presence of a cave and pinpoint its location.

Whatever form the team's robotic explorer ultimately takes, it will have to be agile, have some basic sense of self-awareness, sport excellent night vision and have the ability to communicate with one other in some innovative way, since conventional radio communication might not work well in caves, Cabrol said.

"We are very much on the starting line on this," she added. "This is very exciting. This is really the time when ideas are flitting all over the place."